The, present invention relates to a composite for use as a base material in printed circuit boards (PCBs), antennas and the like, to a base material including the composite and further to electronic modules, such as PCBs, antennas and the like, including the base material. More particularly, the present invention relates to an ultrahigh molecular weight polyethylene (UHMWPE) composite for use as a dielectric in PCBs, antennas and the like. The UHMWPE composite of the present invention is characterized by low dielectric constant and dissipation factor and therefore enables transmitance of high frequency electromagnetic signals with short signal transmission delay times, and possesses desired mechanical properties, such as rigidity and/or flexibility.
A base material for the production of PCBs, antennas and the like, includes a single or a plurality of dielectric layers and electroconductive layers glued bonded or otherwise intimately attached to one another. The dielectric layer(s) provide the required mechanical and dielectric properties to support the functionality of the electroconductive layer(s) in the final product (PCB, antenna and the like).
If high frequency electromagnetic signals with short signal transmission delay times are to be transmitted via the electroconductive layer in the final product, the dielectric layer should be provided with a combination of low dielectric constant (.di-elect cons.) and low dissipation factor (tan .delta.).
Additional properties of the dielectric layer preferably include superior mechanical properties, excellent environmental resistance which is important because tan .delta. is very sensitive to water tracks that may present in the dielectric layer, and good adhesion performances to facilitate effective bonding between the dielectric and electroconductive layers.
Dielectric materials presently used to support high frequency electromagnetic signals in PCBs, antennas and the like are polytetrofluoren (PTFE) [.di-elect cons.=2.2; tan .delta.=0.0002], quartz fibers [.delta.=3.78, tan .delta.=0.0002] and ceramics with low dielectric constant and dissipation factor.
Some of these materials also exist as foam substrates showing even lower dielectric constants.
Different techniques of attaching these materials to an electroconductive layer are also known.
For further detail the reader is referred to U.S. Pat. Nos. 4,772,507; 4,755,911; and 5,141,800, which describe the use of PTFE as a base material for PCBs.
The production, properties and present use of ultra high molecular weight polyethylene (UHMWPE) substrates (e.g., fibers matrix resin) are described in IL 115229; WO 97/11037 and in a review published in the proceedings of the International SAMPLE Symposium (Feb. 9-12, 1992) on pages 1406-1420. These references are hereby incorporated by reference as if fully set forth herein.
UHMWPE has low dielectric constant and dissipation factor [.di-elect cons.=2.2; tan .delta.=0.0002], possesses good mechanical properties and may therefore support transmission of electromagnetic signals at high frequencies with short signal transmission delay times.
Although the use of conventional, low molecular weight foamed polyethylene [.di-elect cons.=1.3, tan .delta.=0.001] in microwave circuit modules was described (U.S. Pat. No. 4,937,585), the prior art fails to teach the use of UHMWPE composite as a base material for PCBs and antennas.
There is thus a widely recognized need for, and it would be highly advantageous to have an ultrahigh molecular weight polyethylene composite for use in a base material for the production of printed circuit boards or antennas, a base material including the composite and electronic modules, such as PCBs, antennas and the like, including the base material, all enjoy the electrical and physical properties of the ultrahigh molecular weight polyethylene composite as further detailed below.